250 Jetting. Does this sound Good?

Brian

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#1
I'm still working on dialing in the jetting on my 01 250 and it seems to get better every time(hey, this jetting stuff aint so bad afterall ;) ) I just wanted to compare my settings with everyone elses to see where I stand. I have been running:

178 main(stock)
45 pilot(stock) w/ AS ~1 out
CEL needle in mid clip-position.

This setup runs very well, but I get a very occasional lean surge, but not NEAR what it used to be. The only time it surges is on decel(closed throttle).

I have the forks off to put new seals in them, and in my boredom and need to tinker with something I raised the needle one clip(as raising the needle from 2 from top to mid has benefited most in the past) and checked my reeds. Reeds are good, but I haven't ridden it yet with the revised needle setting. Does this sound off? I've determined to the best of my knowledge that there's no air leak as well. Zero spooge also. Thanks for your opinions :cool:
 

Brian

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#2
70+ views and no one wants to comment. I just want to know if this is in the ballpark compared to others.
 

Fred T

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#3
OK Stan, I'm gonna bite. We talked at DW '03. You worry too much - OK? If your bike runs pretty good with that jetting then leave it alone. Once you have a base line jet set that you are happy with -leave it alone. When it's hot go leaner on the needle clip and turn the air screw out. When it's cooler raise the needle and turn in the air screw. KTM's have a decel knock, I thought your bike sounded fine at dirtweek. But if you insist, try turning in your air screw 1/8 turn at a time until you feel it go's away. If it don't go away then it probably ain't a problem. OK? Many , many people are using 178 main -45 pilot in 250 KTM's. I don't use straight taper needles so I have no idea how that one works. Maybe you can try a N3CH stock '03 250 needle in #2 for a change of flavor. I ran that in my '03 250 with 40:1 MX2T/93 pump gas.
 

Humai

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#4
Stan, I had an 00 250 EXC (now my bro-in-law's) and ended up with a similar profile of a CGL, 45P and a leaner than normal (must be our fuel) 170M.

The bike still emitted the odd lean knock/surge, but it has always run well since with a minimum of spooge.

I believe that the only way of completely killing the lean surge/single-event-lean-knock-when-easing-off-the-throttle condition is to get the head squish area machined to change the squish dimensions by a reputable specialist. Also, pay particular attention to the X and Z dimensions KTM specifies for that model (in the manual).
 
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#5
I have a 98 250e, so a little different. But I think the L needle may be a little lean. Here is my profile for 3500 ft ele at 60 to 70 degrees.

#7 cut slide
40 pj
CEK-3
175

The 175 is a little fat on top but it is ok, crisp off the bottom, yet no decel knock or run on. Using VP C-12 head cut by Eric Gorr.
 
Last edited:

fishhead

die you sycophant !
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#6
I'm not surprised you have a lean surge with a L needle. I get a surge below 40F with a cek-4. If you cant sleep because of this try a cek-4 with a 45 pilot and 178 main to start. my best guess would be a ddk-3 with a 45 pilot and a 175 main.
If you can't stand the thought of a d taper then get a honda 1369eka and dka and try them in the 2nd position. The eka is the same as the cek ecept it has a very slight transition taper and the start of the taper and the dka is 1/2 clip richer.

The 00 bikes had a 6.0 slide and they will prefer a little leaner needle setup. the 02 bikes have a shorter jetscreen so they prefer a slightly richer setup.

My best setups for tight woods are dck-2 with a 45 pilot and 175 main and a ddk-3 with the same. Roughly sealevel and 40-75f. You will have better response with a k needle versus an L. Try a ddj and dcj for more open terrain.

JET ON!

01 250 exc
 

Brian

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#7
Thanks, guys. As long as I'm in the ballpark, I'm fine with that. I appreciate the input.
 
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#8
Stan try changing the needle first but for our area leave the 178 main in and work out the surge with a needle!